Swine Flu Genome Hints at Milder Virus

Scientists studying the genome of the new swine flu virus
say that it may not be as bad as first feared.

Public-health officials said today that they expect the
virus to continue to spread around the country. However, so far, cases in the United
States appear to be mostly mild, meaning that the ultimate public-health
toll may be no worse than that of the typical seasonal flu, which kills an
average of 36,000 people in the United States each year.

Early analysis of the genome seems to support that idea. According
to an article in the Los
Angeles Times,

“There are certain characteristics, molecular
signatures, which this virus lacks,” said Peter Palese, a microbiologist
and influenza expert at Mt. Sinai Medical Center in New York. In particular,
the swine flu lacks an amino acid that appears to increase the number of virus
particles in the lungs and make the disease more deadly.

Ralph Tripp, an influenza expert at the University of
Georgia, said that his early analysis of the virus’ protein-making instructions
suggested that people exposed to the 1957 flu pandemic–which killed up to 2
million people worldwide–may have some immunity to the new strain. That
could explain why older people have been spared in Mexico, where the swine flu
has been most deadly.

At a press conference today held by the Centers for Disease
Control, acting director Richard Besser said that it’s premature to say anything
about the virulence compared with other strains of influenza based on genetic
analysis.

It’s also too soon to say what might happen over time. For
example, viruses mutate constantly, so it’s possible that this pathogen could become more deadly. “We
are seeing slight changes as it moves through the community, but at this point we
can’t say if those changes impact how severe the virus is,” said Besser at the
press conference.

The 1918 virus began as a relatively mild flu, but then
returned for a more deadly second wave. “If this virus keeps going through
our summer, I would be very concerned,” Palese told the Times.